1 files changed, 509 insertions, 102 deletions

diff --git a/grep.c b/grep.c
index f67d6716ea..90a063a985 100644
--- a/grep.c
+++ b/grep.c
@@ -1,7 +1,21 @@
 #include "cache.h"
 #include "grep.h"
+#include "userdiff.h"
 #include "xdiff-interface.h"
 
+void append_header_grep_pattern(struct grep_opt *opt, enum grep_header_field field, const char *pat)
+{
+	struct grep_pat *p = xcalloc(1, sizeof(*p));
+	p->pattern = pat;
+	p->origin = "header";
+	p->no = 0;
+	p->token = GREP_PATTERN_HEAD;
+	p->field = field;
+	*opt->header_tail = p;
+	opt->header_tail = &p->next;
+	p->next = NULL;
+}
+
 void append_grep_pattern(struct grep_opt *opt, const char *pat,
 			 const char *origin, int no, enum grep_pat_token t)
 {
@@ -15,9 +29,40 @@ void append_grep_pattern(struct grep_opt *opt, const char *pat,
 	p->next = NULL;
 }
 
+struct grep_opt *grep_opt_dup(const struct grep_opt *opt)
+{
+	struct grep_pat *pat;
+	struct grep_opt *ret = xmalloc(sizeof(struct grep_opt));
+	*ret = *opt;
+
+	ret->pattern_list = NULL;
+	ret->pattern_tail = &ret->pattern_list;
+
+	for(pat = opt->pattern_list; pat != NULL; pat = pat->next)
+	{
+		if(pat->token == GREP_PATTERN_HEAD)
+			append_header_grep_pattern(ret, pat->field,
+						   pat->pattern);
+		else
+			append_grep_pattern(ret, pat->pattern, pat->origin,
+					    pat->no, pat->token);
+	}
+
+	return ret;
+}
+
 static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
 {
-	int err = regcomp(&p->regexp, p->pattern, opt->regflags);
+	int err;
+
+	p->word_regexp = opt->word_regexp;
+	p->ignore_case = opt->ignore_case;
+	p->fixed = opt->fixed;
+
+	if (p->fixed)
+		return;
+
+	err = regcomp(&p->regexp, p->pattern, opt->regflags);
 	if (err) {
 		char errbuf[1024];
 		char where[1024];
@@ -41,6 +86,8 @@ static struct grep_expr *compile_pattern_atom(struct grep_pat **list)
 	struct grep_expr *x;
 
 	p = *list;
+	if (!p)
+		return NULL;
 	switch (p->token) {
 	case GREP_PATTERN: /* atom */
 	case GREP_PATTERN_HEAD:
@@ -53,8 +100,6 @@ static struct grep_expr *compile_pattern_atom(struct grep_pat **list)
 	case GREP_OPEN_PAREN:
 		*list = p->next;
 		x = compile_pattern_or(list);
-		if (!x)
-			return NULL;
 		if (!*list || (*list)->token != GREP_CLOSE_PAREN)
 			die("unmatched parenthesis");
 		*list = (*list)->next;
@@ -70,6 +115,8 @@ static struct grep_expr *compile_pattern_not(struct grep_pat **list)
 	struct grep_expr *x;
 
 	p = *list;
+	if (!p)
+		return NULL;
 	switch (p->token) {
 	case GREP_NOT:
 		if (!p->next)
@@ -137,17 +184,33 @@ static struct grep_expr *compile_pattern_expr(struct grep_pat **list)
 void compile_grep_patterns(struct grep_opt *opt)
 {
 	struct grep_pat *p;
-
-	if (opt->all_match)
-		opt->extended = 1;
+	struct grep_expr *header_expr = NULL;
+
+	if (opt->header_list) {
+		p = opt->header_list;
+		header_expr = compile_pattern_expr(&p);
+		if (p)
+			die("incomplete pattern expression: %s", p->pattern);
+		for (p = opt->header_list; p; p = p->next) {
+			switch (p->token) {
+			case GREP_PATTERN: /* atom */
+			case GREP_PATTERN_HEAD:
+			case GREP_PATTERN_BODY:
+				compile_regexp(p, opt);
+				break;
+			default:
+				opt->extended = 1;
+				break;
+			}
+		}
+	}
 
 	for (p = opt->pattern_list; p; p = p->next) {
 		switch (p->token) {
 		case GREP_PATTERN: /* atom */
 		case GREP_PATTERN_HEAD:
 		case GREP_PATTERN_BODY:
-			if (!opt->fixed)
-				compile_regexp(p, opt);
+			compile_regexp(p, opt);
 			break;
 		default:
 			opt->extended = 1;
@@ -155,16 +218,34 @@ void compile_grep_patterns(struct grep_opt *opt)
 		}
 	}
 
-	if (!opt->extended)
+	if (opt->all_match || header_expr)
+		opt->extended = 1;
+	else if (!opt->extended)
 		return;
 
 	/* Then bundle them up in an expression.
 	 * A classic recursive descent parser would do.
 	 */
 	p = opt->pattern_list;
-	opt->pattern_expression = compile_pattern_expr(&p);
+	if (p)
+		opt->pattern_expression = compile_pattern_expr(&p);
 	if (p)
 		die("incomplete pattern expression: %s", p->pattern);
+
+	if (!header_expr)
+		return;
+
+	if (opt->pattern_expression) {
+		struct grep_expr *z;
+		z = xcalloc(1, sizeof(*z));
+		z->node = GREP_NODE_OR;
+		z->u.binary.left = opt->pattern_expression;
+		z->u.binary.right = header_expr;
+		opt->pattern_expression = z;
+	} else {
+		opt->pattern_expression = header_expr;
+	}
+	opt->all_match = 1;
 }
 
 static void free_pattern_expr(struct grep_expr *x)
@@ -223,19 +304,21 @@ static int word_char(char ch)
 	return isalnum(ch) || ch == '_';
 }
 
-static void show_line(struct grep_opt *opt, const char *bol, const char *eol,
-		      const char *name, unsigned lno, char sign)
+static void show_name(struct grep_opt *opt, const char *name)
 {
-	if (opt->pathname)
-		printf("%s%c", name, sign);
-	if (opt->linenum)
-		printf("%d%c", lno, sign);
-	printf("%.*s\n", (int)(eol-bol), bol);
+	opt->output(opt, name, strlen(name));
+	opt->output(opt, opt->null_following_name ? "\0" : "\n", 1);
 }
 
-static int fixmatch(const char *pattern, char *line, regmatch_t *match)
+
+static int fixmatch(const char *pattern, char *line, int ignore_case, regmatch_t *match)
 {
-	char *hit = strstr(line, pattern);
+	char *hit;
+	if (ignore_case)
+		hit = strcasestr(line, pattern);
+	else
+		hit = strstr(line, pattern);
+
 	if (!hit) {
 		match->rm_so = match->rm_eo = -1;
 		return REG_NOMATCH;
@@ -247,29 +330,63 @@ static int fixmatch(const char *pattern, char *line, regmatch_t *match)
 	}
 }
 
-static int match_one_pattern(struct grep_opt *opt, struct grep_pat *p, char *bol, char *eol, enum grep_context ctx)
+static int strip_timestamp(char *bol, char **eol_p)
+{
+	char *eol = *eol_p;
+	int ch;
+
+	while (bol < --eol) {
+		if (*eol != '>')
+			continue;
+		*eol_p = ++eol;
+		ch = *eol;
+		*eol = '\0';
+		return ch;
+	}
+	return 0;
+}
+
+static struct {
+	const char *field;
+	size_t len;
+} header_field[] = {
+	{ "author ", 7 },
+	{ "committer ", 10 },
+};
+
+static int match_one_pattern(struct grep_pat *p, char *bol, char *eol,
+			     enum grep_context ctx,
+			     regmatch_t *pmatch, int eflags)
 {
 	int hit = 0;
-	int at_true_bol = 1;
-	regmatch_t pmatch[10];
+	int saved_ch = 0;
+	const char *start = bol;
 
 	if ((p->token != GREP_PATTERN) &&
 	    ((p->token == GREP_PATTERN_HEAD) != (ctx == GREP_CONTEXT_HEAD)))
 		return 0;
 
- again:
-	if (!opt->fixed) {
-		regex_t *exp = &p->regexp;
-		hit = !regexec(exp, bol, ARRAY_SIZE(pmatch),
-			       pmatch, 0);
-	}
-	else {
-		hit = !fixmatch(p->pattern, bol, pmatch);
+	if (p->token == GREP_PATTERN_HEAD) {
+		const char *field;
+		size_t len;
+		assert(p->field < ARRAY_SIZE(header_field));
+		field = header_field[p->field].field;
+		len = header_field[p->field].len;
+		if (strncmp(bol, field, len))
+			return 0;
+		bol += len;
+		saved_ch = strip_timestamp(bol, &eol);
 	}
 
-	if (hit && opt->word_regexp) {
+ again:
+	if (p->fixed)
+		hit = !fixmatch(p->pattern, bol, p->ignore_case, pmatch);
+	else
+		hit = !regexec(&p->regexp, bol, 1, pmatch, eflags);
+
+	if (hit && p->word_regexp) {
 		if ((pmatch[0].rm_so < 0) ||
-		    (eol - bol) <= pmatch[0].rm_so ||
+		    (eol - bol) < pmatch[0].rm_so ||
 		    (pmatch[0].rm_eo < 0) ||
 		    (eol - bol) < pmatch[0].rm_eo)
 			die("regexp returned nonsense");
@@ -280,7 +397,7 @@ static int match_one_pattern(struct grep_opt *opt, struct grep_pat *p, char *bol
 		 * either end of the line, or at word boundary
 		 * (i.e. the next char must not be a word char).
 		 */
-		if ( ((pmatch[0].rm_so == 0 && at_true_bol) ||
+		if ( ((pmatch[0].rm_so == 0) ||
 		      !word_char(bol[pmatch[0].rm_so-1])) &&
 		     ((pmatch[0].rm_eo == (eol-bol)) ||
 		      !word_char(bol[pmatch[0].rm_eo])) )
@@ -288,55 +405,66 @@ static int match_one_pattern(struct grep_opt *opt, struct grep_pat *p, char *bol
 		else
 			hit = 0;
 
+		/* Words consist of at least one character. */
+		if (pmatch->rm_so == pmatch->rm_eo)
+			hit = 0;
+
 		if (!hit && pmatch[0].rm_so + bol + 1 < eol) {
 			/* There could be more than one match on the
 			 * line, and the first match might not be
 			 * strict word match.  But later ones could be!
+			 * Forward to the next possible start, i.e. the
+			 * next position following a non-word char.
 			 */
 			bol = pmatch[0].rm_so + bol + 1;
-			at_true_bol = 0;
-			goto again;
+			while (word_char(bol[-1]) && bol < eol)
+				bol++;
+			eflags |= REG_NOTBOL;
+			if (bol < eol)
+				goto again;
 		}
 	}
+	if (p->token == GREP_PATTERN_HEAD && saved_ch)
+		*eol = saved_ch;
+	if (hit) {
+		pmatch[0].rm_so += bol - start;
+		pmatch[0].rm_eo += bol - start;
+	}
 	return hit;
 }
 
-static int match_expr_eval(struct grep_opt *o,
-			   struct grep_expr *x,
-			   char *bol, char *eol,
-			   enum grep_context ctx,
-			   int collect_hits)
+static int match_expr_eval(struct grep_expr *x, char *bol, char *eol,
+			   enum grep_context ctx, int collect_hits)
 {
 	int h = 0;
+	regmatch_t match;
 
+	if (!x)
+		die("Not a valid grep expression");
 	switch (x->node) {
 	case GREP_NODE_ATOM:
-		h = match_one_pattern(o, x->u.atom, bol, eol, ctx);
+		h = match_one_pattern(x->u.atom, bol, eol, ctx, &match, 0);
 		break;
 	case GREP_NODE_NOT:
-		h = !match_expr_eval(o, x->u.unary, bol, eol, ctx, 0);
+		h = !match_expr_eval(x->u.unary, bol, eol, ctx, 0);
 		break;
 	case GREP_NODE_AND:
-		if (!collect_hits)
-			return (match_expr_eval(o, x->u.binary.left,
-						bol, eol, ctx, 0) &&
-				match_expr_eval(o, x->u.binary.right,
-						bol, eol, ctx, 0));
-		h = match_expr_eval(o, x->u.binary.left, bol, eol, ctx, 0);
-		h &= match_expr_eval(o, x->u.binary.right, bol, eol, ctx, 0);
+		if (!match_expr_eval(x->u.binary.left, bol, eol, ctx, 0))
+			return 0;
+		h = match_expr_eval(x->u.binary.right, bol, eol, ctx, 0);
 		break;
 	case GREP_NODE_OR:
 		if (!collect_hits)
-			return (match_expr_eval(o, x->u.binary.left,
+			return (match_expr_eval(x->u.binary.left,
 						bol, eol, ctx, 0) ||
-				match_expr_eval(o, x->u.binary.right,
+				match_expr_eval(x->u.binary.right,
 						bol, eol, ctx, 0));
-		h = match_expr_eval(o, x->u.binary.left, bol, eol, ctx, 0);
+		h = match_expr_eval(x->u.binary.left, bol, eol, ctx, 0);
 		x->u.binary.left->hit |= h;
-		h |= match_expr_eval(o, x->u.binary.right, bol, eol, ctx, 1);
+		h |= match_expr_eval(x->u.binary.right, bol, eol, ctx, 1);
 		break;
 	default:
-		die("Unexpected node type (internal error) %d\n", x->node);
+		die("Unexpected node type (internal error) %d", x->node);
 	}
 	if (collect_hits)
 		x->hit |= h;
@@ -347,40 +475,314 @@ static int match_expr(struct grep_opt *opt, char *bol, char *eol,
 		      enum grep_context ctx, int collect_hits)
 {
 	struct grep_expr *x = opt->pattern_expression;
-	return match_expr_eval(opt, x, bol, eol, ctx, collect_hits);
+	return match_expr_eval(x, bol, eol, ctx, collect_hits);
 }
 
 static int match_line(struct grep_opt *opt, char *bol, char *eol,
 		      enum grep_context ctx, int collect_hits)
 {
 	struct grep_pat *p;
+	regmatch_t match;
+
 	if (opt->extended)
 		return match_expr(opt, bol, eol, ctx, collect_hits);
 
 	/* we do not call with collect_hits without being extended */
 	for (p = opt->pattern_list; p; p = p->next) {
-		if (match_one_pattern(opt, p, bol, eol, ctx))
+		if (match_one_pattern(p, bol, eol, ctx, &match, 0))
+			return 1;
+	}
+	return 0;
+}
+
+static int match_next_pattern(struct grep_pat *p, char *bol, char *eol,
+			      enum grep_context ctx,
+			      regmatch_t *pmatch, int eflags)
+{
+	regmatch_t match;
+
+	if (!match_one_pattern(p, bol, eol, ctx, &match, eflags))
+		return 0;
+	if (match.rm_so < 0 || match.rm_eo < 0)
+		return 0;
+	if (pmatch->rm_so >= 0 && pmatch->rm_eo >= 0) {
+		if (match.rm_so > pmatch->rm_so)
+			return 1;
+		if (match.rm_so == pmatch->rm_so && match.rm_eo < pmatch->rm_eo)
 			return 1;
 	}
+	pmatch->rm_so = match.rm_so;
+	pmatch->rm_eo = match.rm_eo;
+	return 1;
+}
+
+static int next_match(struct grep_opt *opt, char *bol, char *eol,
+		      enum grep_context ctx, regmatch_t *pmatch, int eflags)
+{
+	struct grep_pat *p;
+	int hit = 0;
+
+	pmatch->rm_so = pmatch->rm_eo = -1;
+	if (bol < eol) {
+		for (p = opt->pattern_list; p; p = p->next) {
+			switch (p->token) {
+			case GREP_PATTERN: /* atom */
+			case GREP_PATTERN_HEAD:
+			case GREP_PATTERN_BODY:
+				hit |= match_next_pattern(p, bol, eol, ctx,
+							  pmatch, eflags);
+				break;
+			default:
+				break;
+			}
+		}
+	}
+	return hit;
+}
+
+static void show_line(struct grep_opt *opt, char *bol, char *eol,
+		      const char *name, unsigned lno, char sign)
+{
+	int rest = eol - bol;
+	char sign_str[1];
+
+	sign_str[0] = sign;
+	if (opt->pre_context || opt->post_context) {
+		if (opt->last_shown == 0) {
+			if (opt->show_hunk_mark)
+				opt->output(opt, "--\n", 3);
+			else
+				opt->show_hunk_mark = 1;
+		} else if (lno > opt->last_shown + 1)
+			opt->output(opt, "--\n", 3);
+	}
+	opt->last_shown = lno;
+
+	if (opt->null_following_name)
+		sign_str[0] = '\0';
+	if (opt->pathname) {
+		opt->output(opt, name, strlen(name));
+		opt->output(opt, sign_str, 1);
+	}
+	if (opt->linenum) {
+		char buf[32];
+		snprintf(buf, sizeof(buf), "%d", lno);
+		opt->output(opt, buf, strlen(buf));
+		opt->output(opt, sign_str, 1);
+	}
+	if (opt->color) {
+		regmatch_t match;
+		enum grep_context ctx = GREP_CONTEXT_BODY;
+		int ch = *eol;
+		int eflags = 0;
+
+		*eol = '\0';
+		while (next_match(opt, bol, eol, ctx, &match, eflags)) {
+			if (match.rm_so == match.rm_eo)
+				break;
+
+			opt->output(opt, bol, match.rm_so);
+			opt->output(opt, opt->color_match,
+				    strlen(opt->color_match));
+			opt->output(opt, bol + match.rm_so,
+				    (int)(match.rm_eo - match.rm_so));
+			opt->output(opt, GIT_COLOR_RESET,
+				    strlen(GIT_COLOR_RESET));
+			bol += match.rm_eo;
+			rest -= match.rm_eo;
+			eflags = REG_NOTBOL;
+		}
+		*eol = ch;
+	}
+	opt->output(opt, bol, rest);
+	opt->output(opt, "\n", 1);
+}
+
+static int match_funcname(struct grep_opt *opt, char *bol, char *eol)
+{
+	xdemitconf_t *xecfg = opt->priv;
+	if (xecfg && xecfg->find_func) {
+		char buf[1];
+		return xecfg->find_func(bol, eol - bol, buf, 1,
+					xecfg->find_func_priv) >= 0;
+	}
+
+	if (bol == eol)
+		return 0;
+	if (isalpha(*bol) || *bol == '_' || *bol == '$')
+		return 1;
 	return 0;
 }
 
+static void show_funcname_line(struct grep_opt *opt, const char *name,
+			       char *buf, char *bol, unsigned lno)
+{
+	while (bol > buf) {
+		char *eol = --bol;
+
+		while (bol > buf && bol[-1] != '\n')
+			bol--;
+		lno--;
+
+		if (lno <= opt->last_shown)
+			break;
+
+		if (match_funcname(opt, bol, eol)) {
+			show_line(opt, bol, eol, name, lno, '=');
+			break;
+		}
+	}
+}
+
+static void show_pre_context(struct grep_opt *opt, const char *name, char *buf,
+			     char *bol, unsigned lno)
+{
+	unsigned cur = lno, from = 1, funcname_lno = 0;
+	int funcname_needed = opt->funcname;
+
+	if (opt->pre_context < lno)
+		from = lno - opt->pre_context;
+	if (from <= opt->last_shown)
+		from = opt->last_shown + 1;
+
+	/* Rewind. */
+	while (bol > buf && cur > from) {
+		char *eol = --bol;
+
+		while (bol > buf && bol[-1] != '\n')
+			bol--;
+		cur--;
+		if (funcname_needed && match_funcname(opt, bol, eol)) {
+			funcname_lno = cur;
+			funcname_needed = 0;
+		}
+	}
+
+	/* We need to look even further back to find a function signature. */
+	if (opt->funcname && funcname_needed)
+		show_funcname_line(opt, name, buf, bol, cur);
+
+	/* Back forward. */
+	while (cur < lno) {
+		char *eol = bol, sign = (cur == funcname_lno) ? '=' : '-';
+
+		while (*eol != '\n')
+			eol++;
+		show_line(opt, bol, eol, name, cur, sign);
+		bol = eol + 1;
+		cur++;
+	}
+}
+
+static int should_lookahead(struct grep_opt *opt)
+{
+	struct grep_pat *p;
+
+	if (opt->extended)
+		return 0; /* punt for too complex stuff */
+	if (opt->invert)
+		return 0;
+	for (p = opt->pattern_list; p; p = p->next) {
+		if (p->token != GREP_PATTERN)
+			return 0; /* punt for "header only" and stuff */
+	}
+	return 1;
+}
+
+static int look_ahead(struct grep_opt *opt,
+		      unsigned long *left_p,
+		      unsigned *lno_p,
+		      char **bol_p)
+{
+	unsigned lno = *lno_p;
+	char *bol = *bol_p;
+	struct grep_pat *p;
+	char *sp, *last_bol;
+	regoff_t earliest = -1;
+
+	for (p = opt->pattern_list; p; p = p->next) {
+		int hit;
+		regmatch_t m;
+
+		if (p->fixed)
+			hit = !fixmatch(p->pattern, bol, p->ignore_case, &m);
+		else {
+#ifdef REG_STARTEND
+			m.rm_so = 0;
+			m.rm_eo = *left_p;
+			hit = !regexec(&p->regexp, bol, 1, &m, REG_STARTEND);
+#else
+			hit = !regexec(&p->regexp, bol, 1, &m, 0);
+#endif
+		}
+		if (!hit || m.rm_so < 0 || m.rm_eo < 0)
+			continue;
+		if (earliest < 0 || m.rm_so < earliest)
+			earliest = m.rm_so;
+	}
+
+	if (earliest < 0) {
+		*bol_p = bol + *left_p;
+		*left_p = 0;
+		return 1;
+	}
+	for (sp = bol + earliest; bol < sp && sp[-1] != '\n'; sp--)
+		; /* find the beginning of the line */
+	last_bol = sp;
+
+	for (sp = bol; sp < last_bol; sp++) {
+		if (*sp == '\n')
+			lno++;
+	}
+	*left_p -= last_bol - bol;
+	*bol_p = last_bol;
+	*lno_p = lno;
+	return 0;
+}
+
+int grep_threads_ok(const struct grep_opt *opt)
+{
+	/* If this condition is true, then we may use the attribute
+	 * machinery in grep_buffer_1. The attribute code is not
+	 * thread safe, so we disable the use of threads.
+	 */
+	if (opt->funcname && !opt->unmatch_name_only && !opt->status_only &&
+	    !opt->name_only)
+		return 0;
+
+	/* If we are showing hunk marks, we should not do it for the
+	 * first match. The synchronization problem we get for this
+	 * constraint is not yet solved, so we disable threading in
+	 * this case.
+	 */
+	if (opt->pre_context || opt->post_context)
+		return 0;
+
+	return 1;
+}
+
+static void std_output(struct grep_opt *opt, const void *buf, size_t size)
+{
+	fwrite(buf, size, 1, stdout);
+}
+
 static int grep_buffer_1(struct grep_opt *opt, const char *name,
 			 char *buf, unsigned long size, int collect_hits)
 {
 	char *bol = buf;
 	unsigned long left = size;
 	unsigned lno = 1;
-	struct pre_context_line {
-		char *bol;
-		char *eol;
-	} *prev = NULL, *pcl;
 	unsigned last_hit = 0;
-	unsigned last_shown = 0;
 	int binary_match_only = 0;
-	const char *hunk_mark = "";
 	unsigned count = 0;
+	int try_lookahead = 0;
 	enum grep_context ctx = GREP_CONTEXT_HEAD;
+	xdemitconf_t xecfg;
+
+	opt->last_shown = 0;
+
+	if (!opt->output)
+		opt->output = std_output;
 
 	if (buffer_is_binary(buf, size)) {
 		switch (opt->binary) {
@@ -395,15 +797,36 @@ static int grep_buffer_1(struct grep_opt *opt, const char *name,
 		}
 	}
 
-	if (opt->pre_context)
-		prev = xcalloc(opt->pre_context, sizeof(*prev));
-	if (opt->pre_context || opt->post_context)
-		hunk_mark = "--\n";
+	memset(&xecfg, 0, sizeof(xecfg));
+	if (opt->funcname && !opt->unmatch_name_only && !opt->status_only &&
+	    !opt->name_only && !binary_match_only && !collect_hits) {
+		struct userdiff_driver *drv = userdiff_find_by_path(name);
+		if (drv && drv->funcname.pattern) {
+			const struct userdiff_funcname *pe = &drv->funcname;
+			xdiff_set_find_func(&xecfg, pe->pattern, pe->cflags);
+			opt->priv = &xecfg;
+		}
+	}
+	try_lookahead = should_lookahead(opt);
 
 	while (left) {
 		char *eol, ch;
 		int hit;
 
+		/*
+		 * look_ahead() skips quicly to the line that possibly
+		 * has the next hit; don't call it if we need to do
+		 * something more than just skipping the current line
+		 * in response to an unmatch for the current line.  E.g.
+		 * inside a post-context window, we will show the current
+		 * line as a context around the previous hit when it
+		 * doesn't hit.
+		 */
+		if (try_lookahead
+		    && !(last_hit
+			 && lno <= last_hit + opt->post_context)
+		    && look_ahead(opt, &left, &lno, &bol))
+			break;
 		eol = end_of_line(bol, &left);
 		ch = *eol;
 		*eol = 0;
@@ -433,11 +856,13 @@ static int grep_buffer_1(struct grep_opt *opt, const char *name,
 			if (opt->status_only)
 				return 1;
 			if (binary_match_only) {
-				printf("Binary file %s matches\n", name);
+				opt->output(opt, "Binary file ", 12);
+				opt->output(opt, name, strlen(name));
+				opt->output(opt, " matches\n", 9);
 				return 1;
 			}
 			if (opt->name_only) {
-				printf("%s\n", name);
+				show_name(opt, name);
 				return 1;
 			}
 			/* Hit at this line.  If we haven't shown the
@@ -446,45 +871,20 @@ static int grep_buffer_1(struct grep_opt *opt, const char *name,
 			 * the context which is nonsense, but the user
 			 * deserves to get that ;-).
 			 */
-			if (opt->pre_context) {
-				unsigned from;
-				if (opt->pre_context < lno)
-					from = lno - opt->pre_context;
-				else
-					from = 1;
-				if (from <= last_shown)
-					from = last_shown + 1;
-				if (last_shown && from != last_shown + 1)
-					printf(hunk_mark);
-				while (from < lno) {
-					pcl = &prev[lno-from-1];
-					show_line(opt, pcl->bol, pcl->eol,
-						  name, from, '-');
-					from++;
-				}
-				last_shown = lno-1;
-			}
-			if (last_shown && lno != last_shown + 1)
-				printf(hunk_mark);
+			if (opt->pre_context)
+				show_pre_context(opt, name, buf, bol, lno);
+			else if (opt->funcname)
+				show_funcname_line(opt, name, buf, bol, lno);
 			if (!opt->count)
 				show_line(opt, bol, eol, name, lno, ':');
-			last_shown = last_hit = lno;
+			last_hit = lno;
 		}
 		else if (last_hit &&
 			 lno <= last_hit + opt->post_context) {
 			/* If the last hit is within the post context,
 			 * we need to show this line.
 			 */
-			if (last_shown && lno != last_shown + 1)
-				printf(hunk_mark);
 			show_line(opt, bol, eol, name, lno, '-');
-			last_shown = lno;
-		}
-		if (opt->pre_context) {
-			memmove(prev+1, prev,
-				(opt->pre_context-1) * sizeof(*prev));
-			prev->bol = bol;
-			prev->eol = eol;
 		}
 
 	next_line:
@@ -495,7 +895,6 @@ static int grep_buffer_1(struct grep_opt *opt, const char *name,
 		lno++;
 	}
 
-	free(prev);
 	if (collect_hits)
 		return 0;
 
@@ -503,17 +902,25 @@ static int grep_buffer_1(struct grep_opt *opt, const char *name,
 		return 0;
 	if (opt->unmatch_name_only) {
 		/* We did not see any hit, so we want to show this */
-		printf("%s\n", name);
+		show_name(opt, name);
 		return 1;
 	}
 
+	xdiff_clear_find_func(&xecfg);
+	opt->priv = NULL;
+
 	/* NEEDSWORK:
 	 * The real "grep -c foo *.c" gives many "bar.c:0" lines,
 	 * which feels mostly useless but sometimes useful.  Maybe
 	 * make it another option?  For now suppress them.
 	 */
-	if (opt->count && count)
-		printf("%s:%u\n", name, count);
+	if (opt->count && count) {
+		char buf[32];
+		opt->output(opt, name, strlen(name));
+		snprintf(buf, sizeof(buf), "%c%u\n",
+			 opt->null_following_name ? '\0' : ':', count);
+		opt->output(opt, buf, strlen(buf));
+	}
 	return !!last_hit;
 }